Mechanical strain increases expression of type XII collagen in murine osteoblastic MC3T3-E1 cells.
In adult mouse, the mRNA corresponding to the alpha1 chain of type XII collagen (alpha 1(XII)) is predominantly detected in the bone. Additionally, murine osteoblastic cells, MC3T3-E1, increased the mRNA level of alpha 1(XII) response to the mechanical strain in the stretch culture system. Cyclic stretch stress resulted in a threefold increase in mRNA level of alpha 1(XII) as compared to the control experiment in MC3T3-E1. Transient transfection assays employing a reporter construct, together with site-directed mutagenesis studies, suggested that the AP-1 binding site in the first exon of mouse alpha 1(XII) gene is important for stretch stress-mediated upregulation of alpha 1(XII) expression. Electrophoretic mobility shift assay and associated antibody supershift experiments showed that stretch stress promotes the binding of c-Jun and JunD. Further chromatin immunoprecipitation experiments confirmed the participation of these transcription factors in the region. Also, the exogenous induction of the dominant negative form of c-Jun canceled the effect of stretch stress on the stimulation of the alpha 1(XII) gene. Here, we reported a potential responsive element to the stretch stress in mouse alpha 1(XII) gene. These data will provide new information on the mechanical strain-mediated transcriptional control of alpha 1(XII)-mediated fibrillogenesis in the bone.
Arai
Katsuhiko
K
Department of Tissue Physiology, Tokyo University of Agriculture and Technology, Tokyo, Japan. karai@cc.tuat.ac.jp
Nagashima
Yuko
Y
Takemoto
Taeko
T
Nishiyama
Toshio
T
D000818:Animals; D001483:Base Sequence; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D024082:Collagen Type XII / Q000235:genetics*; D005091:Exons; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013314:Stress, Mechanical; D015854:Up-Regulation
D024082:Collagen Type XII; D012333:RNA, Messenger